US 2008/0014068 discloses a device for accommodating two vehicles, for instance snowmobiles, positioned above each other. The device is intended to be positioned on a pickup or any other kind of vehicles. The device comprises two front uprights and two rear uprights extending upwardly from a lower loading plate. An upper loading plate is rotatably attached to the front uprights and slidable on the rear uprights between an upper position and a lower position. The upper loading plate can be raised upwardly and lowered by means of a winch.
U.S. Pat. No. 4,880,250 discloses a boat trailer having an upper loading plate and a lower loading plate. The upper loading plate is rotatably attached to a forward structure which extends upwardly from the lower loading plate. The upper loading plate may be lowered for receiving for instance a boat, see FIGS. 1 to 7. When the upper loading plate with the boat has been returned to an upper position a vehicle can be driven in onto the lower loading plate of the trailer.
U.S. Pat. No. 4,749,317 discloses a trailer having a fixed device comprising a lower loading plate for a vehicle and an upper loading plate for another vehicle. The upper loading plate is rotatably attached onto a frame around an axis located behind the front end of the upper loading plate. The trailer also comprises a ramp which can be used for loading the vehicles onto the lower loading plate and onto the upper loading plate. In addition, the ramp may be raised against the upper loading plate and may be locked to the upper loading plate when this is located in the upper position.
GB-711 289 discloses a larger trailer for receiving a plurality of cars, such as two cars on a lower loading plate and two on an upper loading plate. The trailer comprises at least hydraulic cylinder for displacement of the upper loading plate between a lower position and an upper position.